The proposed research will test the segmentation hypothesis in young dyslexics by assessing the nature of their underlying phonological representation. In order to establish convergent validity, three tasks that are not confounded by metalinguistic, temporal or articulatory confounds will be used to measure implicit phonological representations. Dyslexic's performance on a syllable similarity task, a agate lexical retrieval task, and a priming task will be compared to chronological and reading age matched controls (n-25 in each group), in order to ascertain whether their underlying phonological development is delayed or deviant. The level of functioning on these measures of underlying phonological development will be related to performance on a labeling paradigm that evaluates developmental changes in the weights given to different acoustic cues in the perception of speech. In order to assess whether deficient phonological representations are a primary cause of dyslexia, the relationship and measures of phoneme awareness, reading ability and other associated features of dyslexia (rapid naming, short term verbal memory, and non-word repetition deficits) will be described. Understanding the nature of phonological development beneath the level of phoneme awareness is important for the development of more effective intervention and prevention strategies for dyslexic individuals.